What is an Electronic Speedometer?

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  • Written By: Patrick Roland
  • Edited By: Kathryn Hulick
  • Last Modified Date: 28 September 2019
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The speedometer is an essential component of any motor-driven vehicle because it measures its speed. For nearly a century analog equipment was used to gauge how fast a vehicle was moving, until electronic speedometer technology became readily available. These devices provide more accuracy and reliability than older models, but maintain the familiar layout of a traditional speedometer. In addition to the speed, electronic speedometers measure RPMs and even distance driven with digital precision. Today, these devices are found in many wheeled and non-wheeled vehicles.

A speedometer is a measuring device for a vehicle's speed and normally measures that speed by having a needle move along a circular path, like a clock hand, indicating how fast a motor is propelling a vehicle. The first speedometers, used in the early 1900s, had a rotating cable attached to the engine's transmission. The electronic speedometer, first utilized in the 1980s, may look like a traditional speedometer or be an LCD screen of numbers. It also takes readings from the transmission, but in a very different way.


The electronic speedometer depends on an electronic rotation sensor placed near the engine's transmission. The sensor is usually a toothed metal disc set between the coil and magnetic field sensor. As the engine operates, the magnetic field delivers a pulse to the sensor. The pulses given off correspond to the rotational speed of the drive shaft. This data is fed into the speedometer's internal computer and calculated out by converting rotations to miles or kilometers per hour.

Modern speedometers do not depend on analog methods to read the drive shaft's spinning, so these devices provide more accurate readings. Another benefit of the electric sensor, compared to the spinning cable, is longevity because traditional speedometers would wear out much faster. Electronic speedometers also provide tachometer and odometer readings with equal accuracy. For these reasons, many older vehicles exchange analog models for electronic speedometers.

An electronic speedometer is customarily thought of as a part of cars and trucks. This is true, because almost all modern automobiles use electronic speed measuring devices, but is not the only place these tools are utilized. An electronic motorcycle speedometer is another common sight with two-wheeled vehicles. In addition, airplanes accurately measure air speed with these tools, as do motorboats.


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